Alpha-lytic protease (aLP) is a bacterial serine protease that belongs to the same family as the mammalian serine proteases trypsin and chymotrypsin. It is synthesized with an amino-terminal pro region, which is required for maturation of the protease in vivo. In vitro, the pro region is a potent inhibitor of the mature protease, and it has also been shown to catalyze the folding of aLP. I am part of a three-person team working on the crystal structure of the aLP/Pro complex. The structure is expected to yield insight into the mechanisms of folding catalysis and of inhibition by the pro region. Since the presence of a pro region appears to be conserved across protease families, and many of these pro regions are also inhibitors and/or folding catalysts, the knowledge gained from this crystal structure may be widely applicable. The GCG sequence analysis package through my Computer Graphics Laboratory account is an invaluable resource for this project. I use it regularly to calculate the molecular weights of aLP/Pro mutants used in the structural determination and to perform sequence alignments with related proteases to extract homology information, to name two of the common tasks. The easily accessible package through CGL is the fastest and most convenient way to perform these routine calculations.